> From: Stefan Keller <sfkel...@gmail.com> > Subject: [gdal-dev] PGeo: reading circular arcs - how? > To: gdal-dev@lists.osgeo.org > > > Hi all > > I have an ESRI Personal GeoDatabase .mdb file (PGeo) which I would > like to read and convert e.g. to Shapefile. > The PGeo file contains "circular arc"s (or circular curve) and since > OGR only supports linestrings they should be segmented (similar to > http://www.gdal.org/ogr/drv_ili.html ). > > Now it turned out that the output is wrong: It seems that at least the > midpoint(s) are misinterepreted. > > In fact, when looking at the source (line 430 ff.) there's a TODO there: > http://trac.osgeo.org/gdal/browser/trunk/gdal/ogr/ogrsf_frmts/pgeo/ogrpgeolayer.cpp > > ESRI user doc says at > http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//002t0000000m000000.htm > "Circular arc curves use a mathematical formula to draw the curve. If > you export a geodatabase feature class containing circular > arc curve features to a shapefile, the curved features are transformed > to simple line features with closely spaced vertices to capture the > curved shape". > > => Does anybody know this formula
http://resources.esri.com/help/9.3/ArcGISEngine/java/api/arcobjects/com/esri/arcgis/geometry/IPolycurve.html#densify(double,%20double) > and/or the meaning of the > additional attributes in the byte stream? > depends on the type of curve. It could be a bezier curve, elliptical arc or circular arc. if you look at the coclasses of Icurve http://edndoc.esri.com/arcobjects/9.2/ComponentHelp/esrigeometry/ICurve.htm you will find attributes defined on those specific types that are most likely the serialized bytes. not fun. good luck, Ragi_______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
